- Histological confirmation of a high-grade malignant glioma is required. Histologic diagnoses include, but are not limited to, anaplastic astrocytoma and glioblastoma multiforme. Patients with DIPG are exempt from histologic verification if they have typical MRI findings of DIPG (i.e. hypo- or isointense on T1-weighted imaging, hyperintense on FLAIR or T2-weighted imaging, epicenter in the pons, greater than 50% of pons involved) in the face of a typical clinical presentation.